The test flight ended in disaster.. it started well enough.. had positive control for about 5 minutes, one thing I noticed with a low kv motor is the slow control response which I think I can get used too anyway. Disaster struck when one of the props shattered mid flight.. I suspect I over screwed the plastic prop and it probably had a crack. The quad fell like a rock from approx 20ft. and landed on its back. 3 of 4 of the motormounts broke off..the motors adapters were damaged though the gps, apm and escs seems to be ok.
Important lesson here is: use CF props on the get go AND if possible use the appropriate prop adapter! yes even prop adapters have CW and CCW shaft threads!
Heres the scene of the disaster..landed where it can do the most damage…on the cement runway =(
The Hobbyking H4 Copter Multi-Rotor Quadcopter Frame 470mm is well crafted. Carbon fiber motor and body plates with aluminum arms and frame. My only gripe is the motor plates where you screw the motors on.. it would have been perfect if it can readily accommodate the Turnigy Multistar 3508-640Kv 14Pole Multi-Rotor Outrunner.
The new wings I’ve been working on for the last couple of weeks was well worth it.
Here it is last night, with the skin on:
And finally, this morning ater a successful flight:
The 1.4kv turnigy aerodrive motor, 10×6 prop and 5000mah battery gives ample thrust.. the plane can fly really fast.
Stall speed is low.. even lower (it seems) than my 1.4m hitec skyscout. No doubt the airfoil (as close to NACA 4412 in case you’re interested) made a huge difference.
However throttling up causes the plane to pitch down negating the lift.. nothing which some up elevator cant fix though. It looks like I need to put in some more down angle to the motor now that the CG is known.
The elevator also needs to be secured more firmly to prevent it from rolling (wagging really) which affects the flight characteristics somewhat specially when banking.
I began making a scratch-built Skywalker (SW) rc plane based on plans from rcgroups. “IF” it flies and wont weigh a ton from my usual over design tendencies ill be using it for long range. My target is it should have a base, empty weight (sans ALL electronics) of not more than 600g 800g*. Or a total flying weight of not more than 2.2Kg fully loaded with all the RC, Servos, 5000mah 4S LiPo, APM2.6 and FPV gear etc.
So far I’m done with the cutting of the main wings and tail assembly (rudder and elevator) which took a ridiculous amount of time: I couldn’t decide whether to put the elevator on top of the rudder (like the pre-CF tail 2013 SW) or below the tail (somewhat like the 2013 SW). Eventually decided to do the latter so i won’t have to strengthen the rudder too much. The downside is the elevator will now be more prone to landing (or crash!) damage.
Here’s the tail section:
A closer look at the the attachment points: the end of the tail spar on the right end is a ballpoint pen casing where a barbeque stick glued to the CF spar can be inserted. This is secured by PVC/plastic strips glued to the elevator and secured to the base of the rudder with a screw and nut.
..and attached to the base of the fuselage last night:
Target Empty Weight: 600g 800g. Weight at this stage: 175g
With the addition of the EzUHF transmitter, my LRS FPV portable ground station is complete:
1) Spektrum DX6I
2) ezUHF Transmitter
3) 7″ LCD monitor
4) CF mounting for monitor
5) 12V UBEC for powering all the electronics
6) 5.8GHz Video Reciver
7) Portable DVR (on top of the monitor hood)
8) 3S 1600mah LiPO (temporary setup, I’ll eventually use a 4S 1600-2200mah to get good 12v)
9) Acrylic plastic for the EzUHF mount.
I’ve tested this setup more than week ago and was very happy with the FPV. However, the test flights were not that far, not more than 300m from home-base and the ezUHF was only transmitting at ‘LOW’ power. So now that works.. the next is to integrate APM2.6!
I got the ImmersionRC EZUHF transmitter and diversity receiver a couple of weeks ago. The transmitter package includes: the antenna, the transmitter box, head tracker cable, power cable with an open wire, and a transmitter to rc controller cable (in this case for a futaba). Obviously, since I’m using a Spektrum 6i I have to replace the futaba plug with a 3.5mm mono plug for the 6i’s trainer port.
The receiver comes with a data cable (for EzOSD which I didnt get) and the two diversity antennas.
The first thing I did was upgrade the firmware of the BOTH (must be the same FW version) the transmitter and receiver to v1.43 which includes their ‘Extreme Hopping’ mode (ie frequency hopping in a larger 20Mhz band instead of the default 2Mhz).
Finally got an SD DVR recorder to record some FPV videos over Britanny RC airfield. The setup has a 2.8mm lens on a 700TVL camera and a 2W 5.8Ghz Video transmitter.
The camera gets totally washed out when it’s pointed directly to the sun (I understand some cameras automatically superimposes a black dot of extremely bright objects like the sun).. not really a big issue.
The stock Yagi Antenna’s on the VTx and VRx are good enough, although once the plane is directly overhead and goes through the ‘donut hole’ video signal is lost. Simply shifting position / angle of the receiver or the Video Receivers antenna easily fixes it though. Circular polarized antennas a.k.a. Cloverleaf should give better performance.
Making a simple power distribution hub is easy. However, to make sure things will work and not result to magic smoke, make sure that:
All electronics that will be used for this must have the same voltage (e.g. all 12v or all 5v)
You MUST know the maximum power draw in Amps of all the components that may or will be connected to this hub. Refer to your electronics documentation to get the maximum amp draw and add them all up.
Next, prepare the materials:
Get a UBEC suitable for a) the voltage and b) the maximum Amp draw of all your components. In this example, I’m making a power distribution for my portable FPV ground station which is attached to my transmitter. My components consists of a 7″ LCD, the AV receiver and (soon!) an EzUHF LRS transmitter.. all of which draws a maximum of 1.8A. This means a 2.5A UBEC at a minimum should be enough (it wont hurt if we get something with a higher Amp output). This 12v 2.5A UBEC from HK is adequate for my purpose.
A male XT60 or Deans plug, a servo extension (this is optional in case you dont want to hardwire distribution plugs to the UBEC) and several female JST cables. Of course this assumes that all your components will have JST male power plugs as well =) Anyway, here’s the materials prior to assembly:
Finally, solder them all together making sure that the positive wires are connected to the correct connectors otherwise.. poof! Ok here’s the end product:
Make sure to use heat shrink tubing to insulate soldered connections.
My FPV kit arrived about a week ago, having opted to get the (relatively) humongous 2W transmitter (at 180g) and which does not have any mounting to speak of.. what you get is an aluminum heat sink and perforated steel sheet casing at the bottom.
Some folks insert steel clamps at the bottom, whatever those are they must really be small and almost impossible to find anywhere. My solution was make a custom mounting made out of PVC sheet using good ‘ol used phone cards (or credit cards). The first thing to that needs to be done is to take the screws off the the fan (dont worry they’re pretty much securely screwed in the aluminum heat sink):
The next step is to cut out some kind of base from the phone card, this will be attached and screwed on top of the fan. Dont worry the screws are long enough for a good secure fit. Here’s the end result:
Now this transmitter is ready to be mounted anywhere!